Effect of interfacial area concentration on one-dimensional code simulation of adiabatic two-phase flows in vertical large size channels

2021 ◽  
Vol 385 ◽  
pp. 111502
Author(s):  
Tetsuhiro Ozaki ◽  
Takashi Hibiki
Keyword(s):  
Interfacial Area ◽  
Two Phase Flows ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
One Dimensional ◽  
Large Size

Interfacial Area Transport of Vertical Upward Annular Two-Phase Flow

2005 ◽  
Author(s):  
Tatsuya Hazuku ◽  
Tomoji Takamasa ◽  
Takashi Hibiki ◽  
Mamoru Ishii
Keyword(s):  
Liquid Film ◽  
Concentration Profile ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
One Dimensional ◽  
Drift Flux Model

Accurate prediction of the interfacial area concentration is essential to successful development of the interfacial transfer terms in the two-fluid model. The interfacial area concentration in annular flow and annular mist flow is especially relevant to the transition process to the liquid film dryout, which might lead to fatal problem in the safety and efficient operation of boiling heat transfer system. However, very few experimental and theoretical studies focusing on the interfacial area concentration in annular flow region have been conducted. From this point of view, accurate measurements of annular flow parameters such as local liquid film thickness, one-dimensional interfacial area concentration of liquid film, and local interfacial area concentration profile of liquid film were performed by a laser focus displacement meter at 21 axial locations in vertical upward annular two-phase flow using a 3-m-long and 11-mm-diameter pipe. The axial distances from the inlet (z) normalized by the pipe diameter (D) varied over z/D = 50 to 250. Data were collected for preset gas and liquid flow conditions and for Reynolds numbers ranging from Reg = 31,800 to 98,300 for the gas phase and Ref = 1,050 to 9,430 for the liquid phase. Axial development of the one-dimensional interfacial area concentration and the local interfacial area concentration profile of liquid film were examined with the data obtained in the experiment. Total interfacial area concentration including liquid film and droplets was also discussed with help of the existing drift-flux model, entrainment correlation, and droplet size correlation.

Numerical Modeling of Two-Phase Flows Using Advanced Two Fluid Systems

2002 ◽  
Author(s):  
Anela Kumbaro ◽  
Imad Toumi ◽  
Vincent Seignole
Keyword(s):  
Fluid Model ◽  
Interfacial Area ◽  
Group Model ◽  
Two Phase Flows ◽  
State Equations ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
Void Fractions ◽  
Two Fluid Model ◽  
Two Fluid

The purpose of this paper is to report on the development and assessment of approximate Riemann solver methods for the discretization of non-linear non-conservative systems arising in the simulation of two-phase flows. These methods are able to treat general two-phase flow systems with realistic state equations and are flexible enough to be applied on any mesh type, structured as well as unstructured. We will detail models that go from the basic 6 equation two-fluid model to the coupling of this system with one or more transport equations, for instance on volumetric interfacial area concentration, or on partial void fractions of groups of bubbles (MUlti-Size-Group model). This kind of transport equation is useful to predict at a finer level the interfacial patterns or bubble size distribution and takes account of coalescence or breakup rates of inclusions. We make a glimpse at the choices made regarding this aspect. Different physico-numerical benchmarks are provided in order to illustrate the numerical and physical modeling. Confrontation with experimental or analytical reference data are performed whenever possible. Computer simulations are performed using OVAP, a new multidimensional CFD code.

A Physically Based, One-Dimensional Two-Fluid Model for Direct Contact Condensation of Steam Jets Submerged in Subcooled Water

2015 ◽  
Vol 1 (2) ◽  
Author(s):  
David Heinze ◽  
Thomas Schulenberg ◽  
Lars Behnke
Keyword(s):  
Direct Contact ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
One Dimensional ◽  
Two Fluid Model ◽  
Contact Condensation ◽  
Two Fluid

A simulation model for the direct contact condensation of steam in subcooled water is presented that allows determination of major parameters of the process, such as the jet penetration length. Entrainment of water by the steam jet is modeled based on the Kelvin–Helmholtz and Rayleigh–Taylor instability theories. Primary atomization due to acceleration of interfacial waves and secondary atomization due to aerodynamic forces account for the initial size of entrained droplets. The resulting steam-water two-phase flow is simulated based on a one-dimensional two-fluid model. An interfacial area transport equation is used to track changes of the interfacial area density due to droplet entrainment and steam condensation. Interfacial heat and mass transfer rates during condensation are calculated using the two-resistance model. The resulting two-phase flow equations constitute a system of ordinary differential equations, which is solved by means of the explicit Runge–Kutta–Fehlberg algorithm. The simulation results are in good qualitative agreement with published experimental data over a wide range of pool temperatures and mass flow rates.

One-dimensional interfacial area transport for bubbly two-phase flow in vertical 5 × 5 rod bundle

2018 ◽  
Vol 72 ◽  
pp. 257-273 ◽  
Author(s):  
Hang Liu ◽  
Liang-ming Pan ◽  
Takashi Hibiki ◽  
Wen-xiong Zhou ◽  
Quan-yao Ren ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Area Transport ◽  
One Dimensional ◽  
Rod Bundle

Axial Development of Vertical Upward Bubbly Flow in a Minipipe

2005 ◽  
Author(s):  
Tatsuya Hazuku ◽  
Naohisa Tamura ◽  
Norihiro Fukamachi ◽  
Tomoji Takamasa ◽  
Takashi Hibiki ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Constitutive Relations ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Measurements ◽  
Local Flow ◽  
Interfacial Area Concentration ◽  
Drift Flux Model

Accurate prediction of the interfacial area concentration is essential to successful development of the interfacial transfer terms in the two-fluid model. Mechanistic modeling of the interfacial area concentration entirely relies on accurate local flow measurements over extensive flow conditions and channel geometries. From this point of view, accurate measurements of flow parameters such as void fraction, interfacial area concentration, gas velocity, bubble Sauter mean diameter, and bubble number density were performed by the image processing method at five axial locations in vertical upward bubbly flows using a 1.02 mm-diameter pipe. The frictional pressure loss was also measured by a differential pressure cell. In the experiment, the superficial liquid velocity and the void fraction ranged from 1.02 m/s to 4.89 m/s and from 0.980% to 24.6%, respectively. The obtained data give near complete information on the time-averaged local hydrodynamic parameters of two-phase flow. These data can be used for the development of reliable constitutive relations which reflect the true transfer mechanisms in two-phase flow. As the first step to understand the flow characteristics in mini-channels, the applicability of the existing drift-flux model, interfacial area correlation, and frictional pressure correlation was examined by the data obtained in the mini-channel.

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